Enlarge / The fish in question, with the ammonite located just below its spine. (credit: Cooper, et. al.)

Some extinct species left copious fossil remnants of their existence. Ammonites —an extinct type of cephalopod—are one such example. From the Devonian through the Paleocene, wherever ancient seas once covered Earth, one can usually find their coiled shells. So one more exquisitely preserved ammonite isn’t necessarily a big deal.

With the exception, perhaps, of one intact example found in the Posidonienschiefer Formation in Germany, where most ammonite shells are flattened and fragmentary. Now, decades after its original discovery, scientists have taken a more careful look at the well-preserved ammonite and the fossil fish it was seemingly nestled against. What they found surprised them: the fish had actually swallowed the large ammonite—something we’ve never seen before, even in fossils of much larger marine species that we know attempted to feed on ammonites.

It didn’t work out well for the fish. The size of the ammonite may have caused the fish to drown, or it may have blocked its digestive tract, causing internal bleeding. Drifting down to the seafloor, the fish was eventually buried and fossilized, preserving that ammonite—along with information about the ecosystem it and the fish inhabited—for over 170 million years.

Enlarge / Artist's conception of the newly found species. (credit: Matheus Fernandes)

It was relatively small in comparison to the giants that would follow it later in Earth’s history. With a hip height of approximately 0.3 meters (about a foot) and a length of perhaps a meter (roughly three feet), this ancient reptile existed long before the evolution of the pterosaurs most of us recognize.

Its most striking features are its skull and hands, two body parts that rarely survive fossilization among similar animals this old. The skull consists of a raptorial-like beak without teeth, while its forelimbs end in long fingers with scimitar-like claws. These two surprising features are among many revelations in a paper published Wednesday in Nature.

Venetoraptor gassenae is the name of this new species of lagerpetid, a type of pterosaur precursor that lived about 230 million years ago in Brazil. Named for the district of Vale Vêneto in the same municipality in which the fossil was found—and for the plundering it might have done with its beak and claws ("raptor" is Latin for "plunderer")—it is also named to honor Valserina Maria Bulegon Gassen. Although not a paleontologist herself, the authors note that she is “one of the main people responsible for the CAPPA/UFSM ” (the Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria), a paleontological research support center).

Enlarge / It takes careful study and the right kind of bones to determine how something like this breathed. (credit: Tito Aureliano et. al. )

Somewhere in Earth’s past, some branches on the tree of life adopted a body plan that made breathing and cooling down considerably more efficient than how mammalian bodies like ours do it. This development might not seem like much on the surface, until you consider that it may have ultimately enabled some of the largest dinosaurs this planet has ever known. It was so successful that it was maintained by three different groups of extinct species and continues to exist today in the living descendants of dinosaurs.

Because lungs don’t usually survive fossilization, one might wonder how scientists are able to ascertain anything about the breathing capabilities of extinct species. The answer lies within their bones.

In a suite of papers published in late 2022 and early 2023 , paleontologists examined fossil microstructure within some of the earliest known dinosaurs to determine just how early parts of this system evolved.

Enlarge / The two skeletons are completely intertwined. (credit: Gang Han)

A new fossil described this week captures two intertwined animals caught in a life-or-death struggle right before both were entombed in a volcanic event. Published in Scientific Reports this Tuesday, the fossil doesn’t capture one dinosaur attacking another—rather, the predator in this case is a smaller mammal known as Repenomamus robustus, and it died with its teeth clamped upon the herbivorous Psittacosaurus lujiatunensis , a dinosaur three times its size.

Gut contents from a Repenomamus fossil described in 2005 prove this same mammalian species ate very young and considerably smaller Psittacosaurus . But the remarkable fossil revealed today is the first evidence of any Cretaceous mammal attacking a larger dinosaur. It’s an astounding snapshot of ancient behavior, challenging previous assumptions of predator/prey dynamics millions of years ago.

A final struggle

These two species in the fossil couldn’t be more different. Psittacosaurus is a type of bipedal ceratopsian dinosaur—an early relative of dinosaurs such as Triceratops—with a large beak-like snout and spiky tail bristles. This was a herd animal, and it's the most commonly found fossil in the Lujiatun Member of the Lower Cretaceous Yixian Formation of China. This particular Psittacosaurus was approximately 6.5–10 years old when it died.

Enlarge / That blue tube is actually a very close relative of vertebrates. (credit: Gerard Soury )

Beneath the waves, there are strange, almost alien creatures that raise questions about the evolution of life on Earth and our own earliest origins. The answers might be hiding in tunicates .

Tunicates are filter-feeding invertebrates that include sea squirts and salps. The more common ascidiacean species are sessile and attach to rocks or the seafloor, while the appendicularian species swim freely. Yet all of them spawn as larvae that vaguely resemble tadpoles. Motile tunicates tend to grow into something that looks like a larger version of the larva. The others eventually faceplant onto a surface and absorb their own tails while morphing into a sessile, tubelike form with two siphons.

Despite all this weirdness, there is now strong evidence that tunicates are the closest relatives to vertebrates, but a mystery still surrounds them. How did they evolve, and what did they evolve from? A 500 million-year-old fossil is now telling us more about the evolution of these peculiar life forms.

Enlarge / Artist's reconstruction of the shark as it once lived. (credit: Klug et. al. )

Sharks are largely cartilaginous, a body structure that often doesn’t survive fossilization. But in a paper published in the Swiss Journal of Paleontology, scientists describe an entirely new species of primitive shark from the Late Devonian period, a time when they were just beginning to proliferate in ancient oceans.

The team found several exceptionally well-preserved fossils that include soft tissues such as scales, musculature, digestive tract, liver, and blood vessel imprints. Also preserved: the species’ most distinct feature, widely separated nasal organs, somewhat akin to those on today’s hammerhead sharks. The find suggests that sharks’ finely tuned sense of smell, the subject of urban legends, was already being selected for just as these predators were becoming established.

A key time and a rare find

Christian Klug is the lead author and curator of the Paleontological Institute and Museum at Zurich University. He explained the significance of the Devonian period in the oceans’ history, when life was flourishing and an evolutionary arms race was in full swing. “With increasing competition among predators inhabiting the water column, the entire organism was selected for more efficiency,” he explained. “This affected swimming abilities, feeding apparatus, but also the sensory systems, which are essential to detect prey, to orient themselves in space, and to escape from even larger predators such as the huge placoderm Dunkleosteus and the equally large shark Ctenacanthus .”

(credit: Alex Boersma/PNAS )

The largest shark alive today, reaching up to 20 meters long, is the whale shark, a sedate filter feeder. As recently as 4 million years ago, however, sharks of that scale likely included the fast-moving predator megalodon, famous for its utterly enormous jaws and correspondingly huge teeth.

Because of incomplete fossil data, we're not entirely sure how large megalodon was and can only make inferences based on some of its living relatives, like the great white and mako sharks. But thanks to some new research on its fossilized teeth, we're now fairly confident that it shared something else with these relatives: it wasn't entirely cold-blooded and apparently kept its body temperature above that of the surrounding ocean.

Taking a temperature

Most sharks, like most fish, are ectothermic, meaning that their body temperatures match those of the surrounding water. But a handful of species, part of a group termed mackerel sharks, have a specialized pattern of blood circulation that helps retain some of the heat their muscles produce. This enables them to keep some body parts at a higher temperature than their surroundings. A species called the salmon shark can maintain a body temperature that's 20° C warmer than the sub-Arctic waters that it occupies.

One of the most famous fossils in human evolutionary history is known as " Lucy ," who belonged to an extinct species called Australopithecus afarensis —an early relative of Homo sapiens who was among the first hominins to walk upright. But scientists have long debated the extent of her bipedalism. Now a 3D digital re-creation of Lucy's muscular anatomy, combined with computer simulations, has reaffirmed that she was quite capable of walking fully erect. The results appeared in a new paper published in the journal Royal Society Open Science.

“Lucy’s ability to walk upright can only be known by reconstructing the path and space that a muscle occupies within the body,” said author Ashleigh Wiseman , an archaeologist at Cambridge University. “We are now the only animal that can stand upright with straight knees. Lucy’s muscles suggest that she was as proficient at bipedalism as we are, while possibly also being at home in the trees.”

Lucy's remains were found in 1974 in Ethiopia at a site called Hadar. Several paleoarchaeologists—including Donald Johanson, Mary Leakey, and Yves Coppens—began surveying the site for signs of fossils relating to the origin of humans. The first interesting find occurred in November 1971, when Johanson found a fossilized upper shinbone and, nearby, the lower end of a femur. Now known as AL 129-1 and dating back more than 3 million years, the angle of the knee joint indicated this was a hominin (now known as Australopithecus afarensi s ) capable of walking upright.

Enlarge / Benjamin Waterhouse Hawkins' studio at the Central Park Arsenal in New York City, with models of extinct animals. (credit: Public domain)

The original plans for New York City's Central Park included a Paleozoic Museum at 63rd Street and Central Park West, which would have displayed life-size concrete models of dinosaurs placed in carefully designed dioramas. Those plans were dashed in 1871 when vandals broke into the workshop of the museum's designer, Benjamin Waterhouse Hawkins , and smashed the models with sledgehammers, burying the rubble in the southwestern corner of the park.

The traditional take in paleontology circles is that the man behind the destruction was William "Boss" Tweed , who pretty much ruled the city's Democratic Party political machine at the time with his cronies at Tammany Hall . But a recent paper published in the Proceedings of the Geologists' Association identifies a different culprit: a lawyer and businessman named Henry Hilton , a member of the Tammany Hall contingent who championed plans for what would become the American Museum of Natural History .

Co-authors Victoria Coules and Michael Benton of the University of Bristol in England also found no evidence of a religious motivation for the destruction, i.e., opposition to the then-nascent field of paleontology and its associated implications for evolutionary theory, which were deemed "blasphemous" by some religious leaders. Rather, it seems to have been one of many "crazy actions" by Hilton. "We find that Hilton exhibited an eccentric and destructive approach to cultural artifacts, and a remarkable ability to destroy everything he touched, including the huge fortune of the department store tycoon Alexander Stewart," Coules and Benton wrote. "Hilton was not only bad but also mad."